Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 160732
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
332 AM EDT Sat Mar 16 2024

.SYNOPSIS...
High pressure will briefly build over the Mid-Atlantic today. A
cold front will deliver cooler and blustery conditions heading
into early next week. High pressure will build in from the
southwest by mid-week, then low pressure may follow toward the
end of next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of early this morning, a cold front was moving southeastward
across SE VA away from the local area. In its wake, northerly
winds were ushering in cooler and drier air.

Some stratocumulus may linger through the morning hours,
especially near the Alleghenies, with some high clouds possibly
building in by late in the day. Otherwise, it looks like a sunny
Saturday. Cold advection isn`t terribly strong, and with the sun
and downsloping component to the wind, high temperatures should
still end up above normal for mid-March.

Scattered showers are possible over the Alleghenies after
midnight as a cold front dives in from the Great Lakes.
Otherwise, the region is expected to see increasing clouds with
mild overnight temperatures.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
The cold front will cross the region Sunday, pushing offshore
Sunday night. This will be the leading edge of much cooler
temperatures and blustery conditions. Given the dry air in
place, precipitation is unlikely east of the mountains. After
one more day of above normal high temperatures, things turn much
cooler especially heading into Monday as cold air pushes in.
There may be some opportunities for mountain snow showers
depending on the amplitude and depth of embedded shortwaves in
NW flow in the wake of the cold front. At the moment, periods of
snow showers look relatively brief with light (sub-advisory)
accumulations most likely through Monday night, but there will
be some CAPE/saturation/lift overlay into the DGZ Monday into
Monday night along and west of the Allegheny Front. If these
dynamics can come together long enough and overcome the higher
mid-March sun angle, at least isolated higher amounts would be
possible. In addition, a stray sprinkle or flurry could travel
east of the mountains as inversion heights rise, but again this
will depend on the strength of any forcing waves passing by.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
On Tuesday, while a rex block persists over the western U.S., a
longwave trough will encompass the central/northern Great Plains and
points eastward. This highly amplified flow should keep temperatures
below average as modified Canadian air spills in from the northwest.
Heading toward the middle of the week, deterministic models agree on
some de-amplification of this trough as heights turn slightly more
zonal. At the same time, a stagnant southwestern U.S. closed low
finally makes its eastward push toward the Four Corners. This
particular system is of interest as it may bring wet conditions
toward the end of the work week, possibly into the following
weekend.

Looking more closely at Tuesday`s forecast, behind a series of
cold fronts, the northwesterly flow regime will keep chilly
weather in the picture. Forecast highs sit in the mid 40s to mid
50s, but with wind gusts up to 20 to 25 mph. This would
contribute to wind chills in the 30s to low 40s. Meanwhile,
across the mountains, highs mainly are confined to the 30s with
it feeling more like the teens to mid 20s. Additionally, some
upslope snow showers continue along the Allegheny Front. Amounts
will be determined by the strength and position of the forcing,
direction of the flow, and extent of moisture. And given it is
the Vernal Equinox (March 19), the solar angle should bring an
additional challenge to snow accumulations. Farther east, expect
dry weather with mostly cloudy skies.

For the middle to latter portions of the work week, temperatures
will moderate as thicknesses increase and heights rise. The
uncertainty in the temperature forecast does increase considerably
at this time as shown by the ensemble spread. This variability is
dictated by how much the southwestern U.S. system impacts the local
weather late in the week. Any rainfall likely holds off until
Friday, with further impacts into the weekend. While beyond the
scope of this forecast period, the Climate Prediction Center
continues to highlight a slight threat for heavy rainfall and
strong winds in the March 23-25 period.

&&

.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
VFR conditions are forecast at the TAF sites through Monday
night, with most if not all precipitation relegated to areas
along and west of the Allegheny Front. Passing clouds are
possible at times (both mid/high level clouds and some cumulus
at times). Blustery NW winds take over behind a cold front
Sunday, with gusts to around 30 kts possible at times. Slight
decreases in winds are expected at night, but similar gusts are
possible again during the day Monday when a stray sprinkle or
flurry can`t totally be ruled out.

Any snow shower activity should remain in the Alleghenies on
Tuesday. While some stray flurries could drift off to the east, do
not expect any impacts at the area terminals. Thus, VFR conditions
are anticipated through Wednesday. Skies will be mostly cloudy on
Tuesday, but ceilings should stay VFR. Otherwise, the bigger story
will be the blustery west-northwesterly winds. Afternoon gusts up to
20 to 25 knots are possible on Tuesday. Expect a repeat into
Wednesday as well as an additional cold front pushes through.

&&

.MARINE...
Periods of increased NW flow will necessitate SCAs at times
through early next week. A period of stronger winds is most
likely Monday into Tuesday as cold advection reaches its peak.
It is during this time that gale-force winds are possible. Dry
weather is anticipated this weekend into early next week.

In the wake of multiple cold frontal passages, blustery winds
persist over the area waterways. These west-northwesterly winds may
gust up to 20 to 30 knots on Tuesday, locally a bit higher toward
the southern waters. There will be a potential for gales over this
area through midday Tuesday. Therefore, expect Small Craft
Advisories during this period while the threat for gales will be
monitored. Winds relax a bit into Tuesday night before ramping back
up on Wednesday as the cold front enters the region. Additional
advisories may be needed for Wednesday as well.

&&

.TIDES/COASTAL FLOODING...
Tidal anomalies across the waters have begun to drop given post-
frontal northwesterly flow. This regime does not last too long as
southerlies ensue for the second half of the day. This allows water
levels to rebound into Sunday with a number of tidal sites set to
reach Action stage. The usual sensitive locations like Annapolis,
Straits Point, and the D.C. Southwest Waterfront could reach Minor
on Sunday morning. A shift to northwesterly flow behind this front
should minimize the threat for coastal flooding during the
subsequent high tide.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...Small Craft Advisory from 8 PM this evening to 6 AM EDT Sunday
     for ANZ531>534-537-539>541-543.
     Small Craft Advisory until 8 AM EDT this morning for ANZ533-
     534-537-542-543.

&&

$$

SYNOPSIS...DHOF
NEAR TERM...DHOF
SHORT TERM...DHOF
LONG TERM...BRO
AVIATION...BRO/DHOF
MARINE...BRO/DHOF
TIDES/COASTAL FLOODING...BRO


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